Datasheet
MAX31865
RTD-to-Digital Converter
4Maxim Integrated
Note 2: All voltages are referenced to ground when common. Currents entering the IC are specified positive.
Note 3: Limits are 100% production tested at T
A
= +25°C and/or T
A
= +85°C. Limits over the operating temperature range and rel-
evant supply voltage range are guaranteed by design and characterization. Typical values are not guaranteed.
Note 4: For 15-bit settling, a wait of at least 10.5 time constants of the input RC network is required. Max startup time is calculated
with a 10kω reference resistor and a 0.1µF capacitor across the RTD inputs.
Note 5: The first conversion after enabling continuous conversion mode takes a time equal to the single conversion time for the
respective notch frequency.
Note 6: Specified with no load on the bias pin as the sum of analog and digital currents. No active communication. If the RTD
input voltage is greater than the input reference voltage, then an additional 400µA I
DD
can be expected.
Note 7: All timing specifications are guaranteed by design.
Note 8: Measured at V
IH
= 0.7V x V
DVDD
or V
IL
= 0.3 x V
DVDD
and 10ms maximum rise and fall times.
Note 9: Measured with 50pF load.
Note 10: Measured at V
OH
= 0.7 x V
DVDD
or V
OL
= 0.3 x V
DVDD
. Measured from the 50% point of SCLK to the V
OH
minimum of
SDO.
AC ELECTRICAL CHARACTERISTICS: SPI INTERFACE
(3.0V P V
DD
P 3.6V, T
A
= -40NC to +125NC, unless otherwise noted. Typical values are T
A
= +25NC, V
DD
= V
DVDD
= 3.3V.) (Notes 3
and 7) (Figure 1 and Figure 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Data to SCLK Setup t
DC
(Notes 8, 9) 35 ns
SCLK to Data Hold t
CDH
(Notes 8, 9) 35 ns
SCLK to Data Valid t
CDD
(Notes 8, 9, 10) 80 ns
SCLK Low Time t
CL
(Note 9) 100 ns
SCLK High Time t
CH
(Note 9) 100 ns
SCLK Frequency t
CLK
(Note 9) DC 5.0 MHz
SCLK Rise and Fall t
R
, t
F
(Note 9) 200 ns
CS to SCLK Setup
t
CC
(Note 9) 400 ns
SCLK to CS Hold
t
CCH
(Note 9) 100 ns
CS Inactive Time
t
CWH
(Note 9) 400 ns
CS to Output High-Z
t
CDZ
(Notes 8, 9) 40 ns
Address 01h or 02h Decoded to
DRDY High
t
DRDYH
After RTD register read access (Note 9) 50 ns